The effect of alpha-fetoprotein on the growth of placental cells in vitro.

Cell cultures of early mouse placentae were studied in the presence of mouse amniotic fluid or isolated alpha-fetoprotein (AFP). Four cell types were observed: polygonal cells, giant cells, small round cells and fibroblasts. The number of polygonal cells increased in placental cultures in the presence of amniotic fluid or AFP, suggesting de novo formation and proliferation in vitro.

Structural and microspectrofluorometric studies on glial cells from the periventricular and arcuate nuclei of the rat hypothalamus.

Fluorescence spectroscopy and electron microscopic techniques have been employed to investigate a class of glial cells that is characterized by the presence in their cytoplasm of large fluorescing inclusions that stain with paraldehyde-fuchsin or chrome-hematoxyline-alum. In the periventricular nucleus the cells have been identified as a population of astrocytes whose inclusions emit an orange-red fluorescence. In the arcuate nucleus there are, in addition to an overwhelming majority of such astrocytes, also some microglial cells with similar characteristics.

A new method for measuring radioactivity in select areas of intact tissue sections.

A new technique is described for measuring radioactivity in select areas of intact tissue sections. The method, which makes use of a liquid scintillation counter, also makes possible identification of the studied zones by prestaining.

Energy absorbing capacity of rat tail tendon at various ages.

Fibres from tail tendons of male rats aged 1--18 months were stretched to breaking point by an 'Instron' tensile apparatus. The energy absorbed during stretching of the tendon was calculated. A sharp increase was found in the energy value during the first 6 months of postnatal life.

Changes in the mechanical properties or rat tail tendon during postnatal ontogenesis.

The ultimate tensile strength, elasticity modulus and ultimate elongation of tail tendon in rats age 1-18 months were measured with an Instron tensile apparatus. An increase in all these parameters was observed during the period of maturation, with a later levelling off of the tensile strength and the ultimate elongation. The value of the elasticity modulus attained a maximum during sexual maturation, and then decreased and stabilized.